Police were caught on video using pepper spray on demonstrators outside a Donald Trump rally in Kansas City on Saturday.

A protester filmed the incident while standing in a crowd of demonstrators when police officers, two on horseback, started spraying them. The Twitter user, Chris, and his friends were talking among themselves and at one point jokingly yelled “Save the horse!” in reference to a jittery-looking police horse.

It’s not clear what prompted the officers to do so, but several began spraying the crowd of protesters, moving down the line.

41ActionNews reporter Josh Helmuth was on the scene and based on videos captured on his Twitter feed, the scene was tense outside. A woman told him a fight had broken out, though it was unclear who was involved. Helmuth reported he and the photojournalist accompanying him were hit by the bevy of pepper spray and mace.

Inside the rally, demonstrators repeatedly interrupted Trump, as has become the norm. Trump vowed he wanted to ruin the lives of protesters by pressing charges on them, thus causing them to have arrest records.

“I don’t want to ruin people’s lives,” he said. “But the only way we’re gonna stop this craziness is if we press charges. Because then their lives are gonna be ruined, they’re gonna know their lives are gonna be ruined. So I’ll just tell you folks, from now on, if you do anything, we’re pressing charges, okay?”

Trump said Kansas City officials had suggested he cancel the event out of safety concerns, which the city manager flatly denied.